1. Field of the Invention
The present invention is related to a liquid crystal display (LCD) panel, and more particularly, to an LCD panel that is capable of compensating a feed-through voltage.
2. Description of the Prior Art
Liquid crystal display (LCD) devices, characterized in thin appearance, low power consumption low and no radiation, have been widely used in electronic products, such as computer screens, mobile phones, personal digital assistances (PDA), flat-panel televisions, etc. An LCD device includes a thin film transistor (TFT) substrate, a color filter substrate, and a liquid crystal layer sandwiched between the two substrates. The rotation angle of the liquid crystal molecules is changed by changing the voltage potential between the two substrates. Various images may thus be displayed by changing the transmittance of the liquid crystal layer.
Please refer to FIG. 1. FIG. 1 is a diagram of a conventional TFT LCD panel. A display panel 10 includes a plurality of scan lines G1-Gm, a plurality of data lines S1-Sn, and a plurality of pixels. Each pixel includes a transistor 12, a storage capacitor 14, and a liquid crystal capacitor 16. A parasitic capacitance 18 exists between a gate and a drain of the transistor 12. Taking the pixel coupled with the scan line G1 and the data line S1 as an example, the gate of the transistor 12 is electrically coupled to the scan line G1, the source of the transistor 12 is electrically coupled to the data line S1, and the drain of the transistor 12 is electrically coupled to the electrode of the pixel, that is, a first end of the storage capacitor 14 and the liquid crystal capacitor 16. The liquid crystal capacitor 16 is an equivalent capacitor formed by the liquid crystal layer sandwiched between the two substrates of the display panel 10. The voltage applied to the first end of the liquid crystal capacitor 16 is referred to as pixel voltage. The storage capacitor 14 is utilized to store the pixel voltage until the next data signal is inputted. The voltage applied to the second end of the liquid crystal capacitor 16 is referred to as a common voltage VCOM. Usually, the voltage on the second end of the storage capacitor 16, Vcst, is the same as the common voltage VCOM. Sometimes, the voltage Vcst may be adjusted in order to provide different display characteristics.
Please refer to FIG. 2. FIG. 2 is a voltage wave diagram of the display panel 10 in FIG. 1. When the scan line voltage 22 is raised from Vgl to Vgh, the transistor 12 is turned on, the data line voltage 24 charges the pixel electrode during the active period Ton of the scan line voltage 22, and the pixel voltage is raised from Vdl to Vdh then. After the active period Ton of the scan line voltage 22, the scan line voltage 22 drops to Vgl, thereby turning off the transistor 12 and preventing the data line from being charged. When the data line voltage 24 drops from Vdh to Vdl, the storage capacitor 16 keeps the pixel voltage at Vdh, such that the pixel voltage 26 does not drop to Vdl immediately. However, when the scan line voltage 22 drops from Vgh to Vgl, the pixel voltage 26 is pulled down by a feed-through voltage ΔVp due to the coupling of the parasitic capacitance 18. The feed-through voltage ΔVp may cause flicker in TFT LCD displays.